1. Field of the Invention
This invention relates to docking stations for portable computers, and more particularly, to peripheral interfaces within a docking station.
2. Description of the Related Art
The demand for new features and the ability to easily connect peripheral devices to computer systems has led to several new developments in computer systems in recent years. One such development is the Universal Serial Bus (USB). The USB specification was developed in order to provide an external expansion bus which allowed peripheral devices to be added with the same ease as connecting a telephone to a wall jack. Since its introduction, USB has enjoyed widespread acceptance in the marketplace.
As the name implies, USB is a serial bus. A USB peripheral may be easily connected to a computer system by simply plugging its connector into the jack of a USB port. The host computer system may then detect the presence of the newly added peripheral coupled to the USB port. Following detection of the peripheral device, the host computer may then read identification and configuration information from the device, and assign it a unique address for run-time data transfers. The peripheral device may then be ready for operation. In many cases, the only end-user intervention required to make the peripheral device ready for operation is the plugging in of its connector into the USB port.
Because of the ease of connecting USB peripherals, it is often desired to expand the number of USB ports in a computer system. The additional USB ports may be easily provided by a USB hub. FIG. 1 is a block diagram of one embodiment of a computer system having additional USB ports provide by a hub. In the embodiment shown, computer system 100 includes a single USB port, designated as USB port 0. As it may be desirable to connect multiple USB peripherals to computer system 100, USB hub 104 is connected to USB port 0. USB hub 104 includes three additional USB ports, port 1, port 2, port 3, and repeater 104R. Repeater 104R may repeat (i.e. amplify) USB signals being transmitted to or from a peripheral device. Such signals may include both data signals, as well as power signals. Thus, computer system 100 is able to accommodate three USB peripheral devices due to the use of USB hub 104. It should also be noted that additional peripheral devices may be connected to computer system 100 by connecting a second USB hub to the one shown in the drawing.
As the USB standard has increased in popularity, USB controllers for computer systems have been designed to accommodate multiple USB ports. Thus, additional USB ports may be built into the system by simply adding additional USB jacks. While this solution may work well for stationary computer systems (e.g. a desktop computer), it may not be practical for portable computers (i.e. laptops/notebooks). Since a portable computer may be limited in the amount of available physical space, it may not be possible to build additional USB ports into the system. This may be true despite the fact that the USB controller within the system is capable of supporting additional USB ports.
One way in which a portable computer may be able to utilize additional USB ports is through a docking station. However, the docking station must include a hub in order for the portable computer to realize additional USB ports. Placing a hub in a docking station may be more expensive than utilizing the capacity for additional ports provided by the USB controller in the portable computer system. However, due to the physical limitations of the portable computer, it may be necessary to use a docking station with a hub in order to gain access to additional USB ports.
A hub-less docking station for providing additional universal serial bus (USB) ports to a portable computer is disclosed. In one embodiment, a docking station includes a docking connector and a plurality of USB jacks. The docking connector is configured to allow a portable computer to be coupled to the docking station, while the USB jacks are configured for coupling to USB peripherals. The portable computer includes a USB controller configured for supporting a plurality of USB ports. Signal pins from the USB controller are coupled to the USB jacks through the docking connector. Power signals and current sense signals are each multiplexed by a multiplexer in the portable computer, and are each de-multiplexed by a de-multiplexer in the docking station. The de-multiplexed power and current sense signals are provided to the USB jacks. The docking station is thus able to provide a plurality of additional USB ports to the portable computer, when docked, without the use of a USB hub.
The USB controller in the portable computer may be configured to support the USB 2.0 standard, and may also be backward compatible to support the USB 1.1 standard. Embodiments that support future standards of USB are also possible and contemplated. When the portable computer is coupled to the docking station, the host controller may support both those ports that are implemented by connecting to the docking station, as well as any USB ports in the portable computer itself. Thus, the portable computer and the docking station may implement a system having several USB supported only by the USB controller within the portable computer. A repeater or an additional USB controller may not be required in order to implement the additional USB ports in the docking station.